There is known a motor-driven screwdriver having an indicating device that informs an operator about the drive status of the motor-driven screwdriver (Patent Literature 1). The known motor-driven screwdriver has a screwdriver body equipped with an LED indicating that the associated motor is being driven and another LED indicating a state where the motor has been stopped due to the generation of torque greater than a specified value, thereby enabling visual confirmation of the motor drive status.
Meanwhile, a production line for manufacturing a wide variety of products often requires using different tools for manufacturing products of different types. In such a production line, if an operator is left to make a judgment as to which tool should be used to make a particular product, he or she may mistakenly use an improper tool. To prevent such a judgment error, a tool management system has been developed in which a signal is sent to a tool to be used from a control circuit for controlling the operation in the production line (this kind of control circuit will hereinafter be referred to as an “external control circuit”) to light up an LED provided in the tool, thereby informing the operator about the tool to be used (Patent Literature 2).
Not all users using a plurality of tools, e.g. motor-driven screwdrivers, demand the above-described information representing the motor drive status of a motor-driven screwdriver and information indicating which one of the tools should be used. Even if such information is demanded, pieces of information wanted to be indicated differ for each user in most cases. Therefore, in order to meet each user's individual demand, conventional practice is to manufacture a motor-driven screwdriver having a specific indicating function as a specially ordered product. There is also a case where a user wants to add an information indicating function to an already used motor-driven screwdriver afterwards. In such a case, an indicator may be retrofitted to the motor-driven screwdriver. However, motor-driven screwdrivers are available in many specifications and shapes; therefore, it is necessary, in order to retrofit an indicator to an existing motor-driven screwdriver, to manufacture an indicator conforming in shape to each individual motor-driven screwdriver.